Many pesticides including herbicides, fungicides, insecticides, nematocides, etc., are practically insoluble in water and oftentimes may be sparingly soluble in petroleum hydrocarbons, which liquids are both convenient and inexpensive as carriers for providing easily applied pesticide formulations. Because of their insoluble nature, various methods thus have been devised heretofore for applying these pesticidally-active ingredients onto the substrate to be protected. Conventionally, such pesticides have long been applied in rather dilute compositions containing a low percentage of active ingredient. As handling of these dilute compositions and their transport to the point of use is both burdensome and expensive, various improved formulations have been developed which contain insoluble pesticides in concentrated form. Such formulations include, e.g., wettable powders, dust concentrates, aqueous suspensions, and oil/water suspensions.
Wettable powders consist of the active ingredient mixed with a suitable solid carrier and may also contain a surfactant or dispersant. For application, the wettable powder is measured out in certain proportions, is diluted with water, and then stirred to form a suspension. Use of a wettable powder is disadvantageous in that it is somewhat difficult to handle when preparing the suspensions. Further, it has a tendency to cake during storage prior to contact with water, and can be extremely sensitive to high temperatures.
Water-in-oil suspensions wherein the oil is a continuous phase usually are very thick pastes. These are not easily flowable and dispersible in water. Also, they oftentimes may be unstable during storage due to changes in the crystal structure of the pesticide which promote its settling and agglomeration.
Aqueous suspensions of insoluble pesticides heretofore typically have contained only low concentrations of pesticide together with numerous adjuvants for promoting storage stability in the formulation by preventing undue caking and/or agglomeration of the pesticidal component. These suspensions, however, have not consistently possessed good water dispersibility, nor has settling or caking or the pesticide been adequately prevented.
There has long been a need in the art for a flowable aqueous pesticide composition which is easily handled during preparation and use, which has excellent shelf-life even during extended storage and which is completely dispersible in water. Particularly, a flowable, storage-stable and water-dispersible composition which can contain a high concentration of pesticide component, e.g., up to and including about 6 lbs pesticide per gallon of formulation, has long been desired.
The present invention comprises a liquid, easily flowable pesticide composition completely dispersible in water comprising an aqueous suspension of at least one solid, essentially water-insoluble pesticidally-active component, which composition is characterized by excellent storage stability. In addition to the homogeneously dispersed pesticidally-active ingredient, this composition contains a minor quantity each of a heteropolysaccharide gum and at least one nonionic surfactant, and optionally other adjuvants such as anticaking agents, antifoam agents, freeze-thaw depressants, and the like. Most significantly, it retains its outstanding stability and dispersibility characteristics even when incorporating extremely high solids concentration, e.g., up to and including 6 lbs of pesticide per gallon.